A set of IDL routines to define a coupled water-atmosphere system and to drive Radiative Transfer simulations is described. This application takes advantage of IDL 6.0 Object Oriented Programming features in order to allow unified description of the physical system, independent of the code to drive, and to ease the maintenance of and the adaptation to a specific model (FEM, Hydrolight, ...). A common library of routines to analyse the results of the simulations is also implemented.